1. Field of the Invention
The present invention relates to a double progressive spectacle lens.
2. Description of Related Art
A distinction is made between two different types of lens in the case of progressive spectacle lenses of the prior art.
Lenses of type A are described, for example, in European patent EP 0 969 309 B1 from Rodenstock, these lenses having a front surface with a continuously varying surface power (progressive surface), and the eye-side surface being spherically or aspherically fashioned, or torically or atorically fashioned given an astigmatic prescription. Reference is made further to DE 301 69 35 from Carl Zeiss and DE 43 42 234 from Essilor.
Lenses of type B comprise a simple sphere or asphere and a more complex progressive atoric surface, the possibly prescribed cylinder being integrated in the progressive surface. Reference is made here to DE 43 37 369 from Rodenstock and to EP 0 809 126 from Seiko Epson.
Spectacle lenses of type C comprise a sphere or asphere or, in the case of an astigmatic prescription, a torus and a more complex progressive surface, in which case the latter compensates the deficits of the sphere or asphere or of the torus given a prescribed cylinder in the progressive surface. Reference is made here to DE 197 01 312 from Carl Zeiss.
Lenses of type D comprise two progressive surfaces. DE 33 31 757, DE 33 31 763 from Rodenstock and WO 00/55678, WO 01/73499 and WO 01/18591 of Johnson & Johnson describe such spectacle lenses.
All the above described types of lenses have a so-called “hourglass design”. This describes the so-called progression zone, the characteristic vertical restriction in the middle of the lens that widens markedly upward and downward toward the distance zone and near zone.
With spectacle lens of type A and type C, it is absolutely necessary because of the symmetry of the second surface for the surface astigmatism of the progressive surface to have this hourglass shape. Lenses of type B also exhibit the described hourglass shape in the case of spherical prescriptions.
It has now been realized that there is no need to stay with these classic hourglass surfaces. However, it has even been realized that deviating from the hourglass surface shapes is even accompanied by optical and geometric advantages.